1. Field of the Invention
This invention relates generally to disinfection and cleaning systems for medical devices. In a preferred embodiment, the invention relates to compositions, methods and articles for simultaneously cleaning and disinfecting contact lenses.
2. Description of the Related Art
Disinfecting solutions for use with contact lenses are well known in the art and the use of such lenses involves a daily disinfecting treatment. Flexible, or soft, contact lenses are generally made from hydrophilic polymers and the hydroxy groups of these lenses attract and retain substantial amounts of water in the plastic which results in difficulties during cleaning and sterilization.
Hydrogen peroxide systems, particularly 3% hydrogen peroxide solutions, emerged as the disinfectant of choice for all types of daily and extended wear hydrogel lenses. The primary reason for its popularity is its rapid kill of microbial contaminants and its non-residual character. After hydrogen peroxide disinfects lenses, it can be converted into innocuous and natural by-products, such as O2 and water, which are compatible with ocular physiology. See Krezanoski et al., “Journal of the American Optometric Association”, Vol. 59, Number 3, pages 193–197 (1988).
In general, the hydrogen peroxide systems involve a hydrogen peroxide-containing disinfecting solution into which the contact lenses to be disinfected are placed and allowed to remain for a required period of time. The hydrogen peroxide may (1) oxidize chloride in the bacteria to hypochlorite or (2) decompose into nascent oxygen and hydroxyl radicals, thus providing a germicidal effect. Following the requisite time period a purposeful inactivation of the hydrogen peroxide is conducted, for example, with a platinum catalyst. Following inactivation, the contact lens may be reinserted into the eye.
However, harmful microorganisms, proteins, lipids, and other irritating deposits are not always sufficiently removed by peroxide disinfection alone and the lens should be cleaned and rinsed beforehand. This is typically performed by wetting the lens with a sufficient amount of a lens cleaner (such as CIBA Vision® MiraFlow®) and then rubbing the lens with one's fingers and rinsing the lens with saline. The cleaning step is considered a hassle by some consumers and a peroxide disinfection system that adequately disinfects and cleans without this step (a “no rub-no rinse” regimen) would offer a great improvement in convenience to the user.
U.S. Pat. No. 5,523,012 to Winterton, et al. teaches that the addition of a surface-active agent to a peroxide disinfection solution will enhance the disinfecting properties of the solution. However, the surfactants disclosed are all present in amounts above 0.1% and, because of excessive foaming, are incompatible with the platinum catalyst disc typically used to deactivate hydrogen peroxide in lens disinfection systems.
EP0855188 teaches that glycerol, polyhydric alcohol, and Tween 20 will reduce the rate at which hydrogen peroxide will decompose, thus increasing its disinfecting efficacy. However, there are significant problems with each of these compositions that effectively preclude their use in a contact lens disinfection solution. For instance, glycerol is not stable in 3% hydrogen peroxide and both polyhydric alcohol, such as PVA, and Tween 20 will cause excessive foaming when the solution contacts the catalytic disc and decomposes.
U.S. Pat. No. 5,746,972 to Park, et al. teaches compositions and methods for disinfecting and cleaning contact lenses include a liquid medium containing hydrogen peroxide and a solid ethylene oxide/propylene oxide block copolymer surfactant having at least 70% by weight polyethylene oxide. The hydrogen peroxide is degraded by a catalase released into the solution and causes “a reduced amount of foam.” However, such compositions cause excessive foaming when a platinum catalyst is used to decompose the hydrogen peroxide.
In an effort to provide greater convenience, new regimens have been developed. These system provides the benefit of combined “daily” cleaning and disinfection in one non-peroxide solution, wherein the same solution may be directly used in combination with enzymatic cleaners, thus reducing the number of steps and components required for effective lens cleaning and disinfection. However, no such “one-step” regimen exists for hydrogen peroxide systems.
Therefore, it would be advantageous to provide peroxide contact lens disinfection solutions that overcome one or more of these problems.